From 8eae98df6b66e243b4aeea211b84d70a967cda37 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=20van=20Merri=C3=ABnboer?=
 <bart.vanmerrienboer@gmail.com>
Date: Mon, 31 Jul 2017 14:24:32 -0400
Subject: [PATCH] Special case sequence space without elements to make tests
 pass

---
 autograd/container_types.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/autograd/container_types.py b/autograd/container_types.py
index 77ad5cc0..ab313286 100644
--- a/autograd/container_types.py
+++ b/autograd/container_types.py
@@ -66,7 +66,11 @@ def __init__(self, value):
         self.shape = [vspace(x) for x in value]
         self.size = sum(s.size for s in self.shape)
         self.sequence_type = type(value)
-        self.lib = vspace(value[0]).lib
+        if value:
+            # If this a list without elements, we'll just not set the
+            # library; there's a chance this space is nested and that
+            # this won't be needed. Otherwise it'll crash later
+            self.lib = vspace(value[0]).lib
         assert self.sequence_type in (tuple, list)
 
     def zeros(self):